Label verification system using photocell matrices

ABSTRACT

Verification of symbols such as on labels is effected by imaging each label to be verified onto a matrix of photocells and imaging an authentic label onto another matrix of photocells. The outlines of the symbols strike different photocells in the matrices causing a response from each photocell depending on the amount of energy it receives. The output from each photocell is separately amplified, either by individual separate amplifiers or by a single amplifier for each matrix which is electronically scanned across photocell outputs in conventional manner. The outputs from each photocell are limited or otherwise electronically processed so that responses are produced above or below a threshold, depending on whether the photocells encountering the image of the symbols give out more or less energy and these pulses or outputs, which are in digital form, are then compared in a conventional digital comparator. If the label to be verified gives the same signal as an authentic label, the comparator does not have any output and another label can then be verified. If the label is not authentic, an output from the digital comparator sounds an alarm and can remove the container bearing the label from a moving stream. Preferably the symbols contain photoluminescent substances and the matrix of photocells is provided with suitable filters, so that when the labels are illuminated with ultraviolet light photocell responses are at a much higher degree of contrast.

United States Patent [72] Inventor Michael Madalo Whitehouse Station, NJ. [21] Appl. No. 27,899 [22] Filed Apr. 13, 1970 [45] Patented Apr. 6, 1971 [73] Assignee American Cyanamid Company Stamford, Conn.

[54] LABEL VERIFICATION SYSTEM USING PHOTOCELL MATRICES 6 Claims, 3 Drawing Figs.

[52] US. Cl 250/219, 250/209, 340/149, 235/6l.1l [51] Int. Cl G08c 9/06 [50] Field of Search 250/219 (ICR), 219 (ID), 219 (IDC), 219(1), 219 (DOC), 208, 209, 83.3 (UV); 340/149, 146.3 (G); 356/71, 168, l69;235/61.115

[56] References Cited UNITED STATES PATENTS 3,105,908 10/1963 Burkhardt et al 250/219 3,192,505 6/1965 Rosenblatt 340/ 146.3 3,225,175 12/1965 Hyypolainen 235/6l.l1 3,480,785 11/1969 Aufderheide 250/219 LABEL5 T0 195 l/E'fi/F/ED PHOTOCELL MATRIX AMPLIFIER PHOTOC'ELL [fi] MATR/X MASTER LABEL Primary Examiner-Walter Stolwein Att0rneySamuel Branch Walker ABSTRACT: Verification of symbols such as on labels is effected by imagingeach label to be verified onto a matrix of photocells and imaging an authentic label onto another matrix of photocells. The outlines of the symbols strike different photocells in the matrices causing a response from each photocell depending on the amount of energy it receives. The output from each photocell is separately amplified, either by individual separate amplifiers or by a single amplifier for each matrix which is electronically scanned across photocell outputs in conventional manner. The outputs from each photocell are limited or otherwise electronically processed so that responses are produced above or below a threshold, depending on whether the photocells encountering the image of the symbols give out more or less energy and these pulses or outputs, which are in digital form, are then compared in a conventional digital comparator. If the label to be verified gives the same signal as an authentic label, the comparator does not have any output and another label can then be verified. 1f the label is not authentic, an output from the digital comparator sounds an alarm and can remove the container bearing the label from a moving stream. Preferably the symbols contain photoluminescent substances and the matrix of photocells is provided with suitable filters, so that when the labels are illuminated with ultraviolet light photocell responses are at a much higher degree of contrast.

//6 :l/ /3 uni/75k THRESHOLD DIG/ML COMPARATOR LIMITE/i THRESHOLD if OUTPUT 2 Sheets-Sheet 1 INVENTOR. MICHAEL MADALO MWWM ATTORNEY Patented April 6, 1971 2 Sheets-Sheet 2 4 INVENTOR. M/CHAEL MAD/1L0 WMM A 7' TOR/VE Y LABEL VERIFICATION SYSTEM USING PHOTOCELL MATRICES BACKGROUND OF THE INVENTION Verification of labels and other documents presents a considerable problem. This is especially true in the pharmaceuti cal industry where an improperly labeled container can cause serious health problems. Various methods have been used, such as magnetic inks and the like, and it has also been proposed to use a photocell matrix responding to the overall integrated output. These methods have been useful but have presented the problem of spurious or unreliable responses if the equipment used is not kept in extremely sharp adjustment, which is often not practical.

SUMMARY OF THE lNVENTlON The present invention utilizes matrices of photocells, there are two identical matrices on one of which an image of a label or other document to be verified is sharply focused and on the other an image of an authentic or master label. The outputs of the photocells are individually amplified, either by separate amplifiers or by time sharing on a single amplifier, for each matrix which is electronically scanned across photocell outputs. After suitable limiting the outputs of the photocells are in the form of digital pulses. These digital pulses are then introduced into a digital comparator and the signal from the master or authentic label compared with that from the label to be verified. The comparator gives an output if the label is not authentic which can serve as an alarm or can control other equipment, for example devices for removing bottles or other containers on which the unauthentic labels are affixed from a moving stream of containers or otherwise processed to separate from authentically labeled containers. Preferably the digital comparator gives an output when a label is not authentic and no output when it is, but of course the reverse is also useful simply by so setting the comparator. The degree of sharpness is, however, greater, and hence the reliability greater, if the comparator gives the signal only when a label is not authentic.

Containers, the labels of which are to be verified, can move continuously with suitable compensating movements for maintaining the image of the label symbol on the matrix for sufficient time to give a reliable output, or the containers may be moved intermittently and halted briefly for verifying their labels. As the output of the matrix can be very fast, milliseconds or less, the image of the symbol does not have to remain for any significant length of time on the matrix. It is therefore possible with rapidly responding matrices to dispense with any mechanism for maintaining the image of the label stationary. For example, a moving series of containers may actuate a gate when they are opposite the imaging elements which pass on outputs from both matrices. Such a modification is extremely simple and, for many purposes where containers do not need to move at very high speeds, is entirely satisfactory.

Even when single amplifiers are used for each of the two mosaics, electronic scanning is so enormously rapid that the time during which the image of the symbol has to remain on the matrix is not significantly lengthened. Of course, if separate amplifiers for each photocell are provided, the response is even faster, but the cost of the equipment is multiplied and preferably, therefore, for the sake of economy scanning amplifiers are used. lt is not necessary to have a single amplifier which is scanned across the whole of the mosaic, a small number of amplifiers, each receiving output from the photocells of one portion or area of the matrix, may be used and of course are then scanned only over the portion of the photocells from which signals are to be received.

lt is an advantage of the invention that equipment elements such as optical imaging means, photocell matrices, amplifiers, with or without scanning, limiters and digital comparators are conve tional and standard pieces of equipment and in most cases be bought as stock items. This reduces the cost of the system for the invention and it is also helpful when replacement of a piece of equipment is needed.

it is possible to use a very simple and somewhat rudimentary modification. If the labels are provided with symbols which are absorbent in the visible, for example black or a color such as red on a light substrate, when this is imaged on a photocell matrix, the photocells which are struck by the radiation from the outlines of the symbols receive less radiant energy than the photocells on which the portions of the substrate which are not covered by the symbol are imaged. In such a case the limiting of the amplified outputs of the photocells will produce pulses which are below the threshold for the photocells receiving light from the portions of the label which are not covered by the outlines of the symbol. This requires a minimum of optical complications but, while included in the broadest aspects of the present invention, is not preferred. The contrast at the photocells is barely sufficient for reliable differentiation and changes in the intensity of light on the label to be verified and the master label can introduce spurious results. It is therefore preferred to utilize systems in which the contrast between symbol outlines and substrates is sharply increased. This can be effected in a number of ways. One cheap and simple way is to provide colored symbols, for example red, and a complementary filter in front of each photocell matrix. If the sub strate is white, the absorption of reflected light from the symbols is practically zero and there is still sufficient light from the portions of the matrix receiving an image of the substrate so that a sharply enhanced contrast is obtained. Where the label itself has a substrate that is colored, the filter can often be of the same color with the symbols, of course, printed in a complementary color. This arrangement permits still greater contrast. A somewhat similar effect can be produced where the light which is reflected from the label to be verified and from the master label is itself colored. For example, if the symbols are in red and the light illuminating the labels is green, a green filter over each photocell matrix still further increases the intensity of illumination from the portions not covered by the symbol, the additional complications of colored ambient illumination is small. Of course the cost of the filters for the matrices is practically negligible.

Even greater contrast, and hence more reliability, can be effected by an embodiment which is the one that is preferred, although in broader aspects the invention is not limited thereto. This preferred modification involves symbols on labels in photoluminescent materials. When the labels are illuminated with ultraviolet light the symbols photoluminesce in a very definite color and a filter having a corresponding transmission is placed in front of the photocell matrix. Of course the filter should also prevent the passage of ultraviolet light which may be reflected from the substrate. This permits a greatly enhanced contrast, and hence reliability, and provides further basis for differentiating authentic labels from those which are not, even through the symbols on the two labels may be the same.

The photoluminescent materials may be of various types. It is possible to use organic pigments which fluoresce in relatively broad bands. Also it is possible to use narrow band fluorescers, which in general are complexes of lanthanide ions having an atomic number greater than 57 with various ligands and synergic agents. These complexes luminesce in extremely narrow bands and, when teamed with sharp cutting filters, for example conventional interference filters, the contrast with the areas of the label which are not covered by symbols is greatly increased. This permits the ultimate in reliability but does increase somewhat the cost of the symbols as the narrow band photoluminescers are somewhat more expensive that broad band fluorescent organic pigments. The cost, however,- is very small because the area covered by a symbol is not great and, in thecase of labels for pharmaceuticals or other purposes where the danger of a mislabeled container is very great, the increase in cost is practically negligible as compared with the greatly improved reliability.

When broad band fluorescent dyes or pigments are used it is in general desirable to use such fluorescers which luminesce primarily-in wave length regions separated from the blue fiuorescers which are frequently used as optical brighteners for white papers. The filter in front of each photocell should, of course, discriminate as strongly as possible against the wave lengths emitted by optical brighteners as well as against reflected ultraviolet light.

The advantage of additional criteria of authenticity which are given by various photoluminescent materials can be further enhanced by using a somewhat different photoluminescent material for different batches, or for products over a particular period of time such as a month. Then it is also possible to detect labels which might have been counterfeited or applied to the wrong containers. This factor can be further expanded by having a portion of the symbols on a label in one photoluminescent material and another portion in another. For example, the top half of the label might have symbols using a europium complex photoluminescing in the red and v the bottom halfa dysprosium complex luminescing in the golden yellow portion of the spectrum. Of course the matrix would have a filter with two separate zones, each one having the proper transmission for the photoluminescence of the symbol from the corresponding part of the label. These various modifications utilizing filters present no significant complication, because photocell matrices may be provided with simple frames in which a new filter can be easily and rapidly inserted. Filters, even sharp cutting interference filters, are not very expensive and in comparison to the whole equipment represent a negligible increase in cost.

It should be noted that when photoluminescent materials are used in symbols, photocells which receive radiation from the portions of the label covered by the symbol will receive much more energy than from the portions not so covered, and therefore the pulses will be above a threshold rather than below. This, of course, presents no problem as it is merely necessary to adjust the digital comparator suitably.

When photoluminescent materials are used for the symbols, these are usually colorless. In other words, the symbols on the label would not be visible under ordinary light. Sometimes this is desirable and preferred. In some other situations, however, it may be desired to be able to read the symbols under visible light. This, of course, is very simply effected by adding a suitable color or pigment to the inks in which the photoluminescent symbols are printed. When narrow band fluorescers such as complexes ofthe lanthanide ions are used, the most efficient luminescers can be obtained simply as they have been developed for coded ink work, and it is an advantage of the present invention that known highly efficient photoluminescers may be used and it is not necessary to develop new materials.

In general the invention, as in many other systems, is a combination invention and does not depend for patentability on any single element. The possibility of using well known or developed system elements reduces costs and increases flexibility and is a practical advantage.

While the present invention is not limited to the use of any particular photoluminescent material, in the preferred modification where such materialsare used it is often desirable to use narrow band photoluminescent materials for the symbols. A number of typical narrow band complexes of lanthanide ions are described in the US. Pat. No. 3,377,292, Apr. 8, 1968 to Halverson. The present invention is, of course, not limited to the particular materials described in the patent but many of them are very effective and illustrate typical narrow band photoluminescent materials which can be used in the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a purely diagrammatic representation of the principal elements;

FIG. 2 is an elevation of a photocell matrix on which the outline of the symbol is shown; and

FIG. 3 is a semidiagrammatic representation of the portions of the system which image symbols on labels onto the photocells.

DESCRlPTlON OF THE PREFERRED EMBODIMENTS A label to be verified l is on a container, such as a bottle or vial, which is moved along by a conveyor 2, the label being imaged by the optics 3 onto a photocell matrix 4. In FIG. 1 the conveying means are omitted and an arrow substituted which shows the direction the labels move. In FIG. 3 the conveyor and imaging means are shown but in semidiagrammatic form as the exact structure of these well known elements, as such, forms no part of the present invention.

The photocell matrix 4 is provided with a number of photocells 5 arranged in rows and columns. To simplify the drawings a rather small number of photocells is shown on the matrix which, is actual operation, may have a much larger number of photocells to accommodate a bigger label. The individual photocells are about I mm in diameter and each photocell has an output for its individual electrical symbol. As the design of the matrix and the photocells is conventional, the output wires are not shown in order not to confuse the drawings. in FIG. 3 a symbol, the number thirteen, is shown at 6 and it will be seen that it covers the whole column of third and seventh vertical columns of photocell, with other parts of the symbol being imaged on other photocells in other columns.

A master label 7 is imaged on a second photocell matrix 8 which is a duplicate of the matrix 4. This master label and its matrix are also not shown on FIG. 3 for simplicity, as the arrangement is a duplicate of elements 1, 3 and 4 except for the fact, of course, that the master label 7 does not move during the operation of the system. The electrical outputs of the matrix 4 are amplified by the amplifier 9. This may be a single amplifier which is electronically scanned across the outputs of the individual photocells of the matrix 4 or it may be in the form of individual amplifiers, one for each photocell. Since the amplifier is of conventional design, as are the electronic scanning circuits, when a single amplifier is used, the showing is purely in block diagram form on HO. 1, the arrow connecting the matrix (4) to the amplifying system 9 symbolizing the connections from the individual photocells. In a similar manner the outputs of the photocells in the matrix 8 which receives an image of the master label, are amplified by the amplifying system 10, the output of the amplifier systems 9 and R0 are then processed in limiting or threshold circuits 11 and l2 and produce pulses or outputs. Where a single amplifier which scans the photocell outputs is used, there is, of course, a single threshold circuit 11 and 12. If separate amplifiers for each photocell are used or if several amplifiers are used with scanning over particular areas of the matrix, the threshold circuits are duplicated for each amplifier. The output of the threshold circuits is in the form of pulses of definite pulse height and two levels depending on whether the pulse comes from a photocell on which is imaged a part of the outline of a symbol or a photocell on which a portion of the label substrate is imaged. The outputs from the threshold circuits pass to a digital comparator l6 and are controlled by gates 13 and 14 which are opened by switch 15 on the conveyor, which can be seen in HO. 3.

The switch is positioned so the gates open when a label is centered and remain open for the short period of time during which the image of the label is to remain on the matrix. The digital comparator, which is of conventional design, of course, compares the pulses and determines whether the pulses are the same from matrices 4 and 8 or are different. In the first case where the label matches the master label, there is no output signal from the comparator output 17, but if there is not a complete match a signal appears which can be used in any desired manner. lf the symbols are formed with photoluminescent materials, a filter 18 is interposed in front of each photocell matrix and passes light of the wavelength range of the photoluminescence of the material and does pass light of other wavelengths. In this case the labels must be illuminated with ultraviolet light as shown diagrammatically at 19 in FIG. 3. For clarity the lamps are not shown in FIG. 1. Typical photoluminescent materials are quinazolone derivatives such as 2-(2-hydroxyphenyl)6-chloro-4(3H) quinazolone which are described in US. Reissue Pat. No. 26,565. Typical lanthanide ion complexes are europium and dysprosium doped yttrium vanadate complexes.

I claim:

l. A system for verifying labels comprising in combination;

a. a first photocell matrix;

b. means for orienting a label and for imaging it onto the plane of the photocell matrix;

c. means for amplifying the output of each individual photocell,

d. means for limiting said amplified output to produce voltage pulses having a predetermined voltage with respect to a predetermined threshold voltage, whereby signal outputs in each photocell form a series of digital voltages.

. a digital comparator and means for connecting the digital voltage pulses thereto;

a second photocell matrix and a second means for orienting a label and imaging it onto a plane of a second photocell matrix;

. means for amplifying the individual photocell outputs of said matrix;

. means for limiting said amplified outputs to produce voltage pulses with respect to predetermined threshold voltage;

. means for connecting said pulses into the digital comparator and an output from the comparator which depends on the comparison of the digital voltage pulses from the two photocell matrices.

2. A system according to claim 1 in which each photocell matrix is provided with an optical filter increasing the contrast between radiation from symbols on the label and from the label substrate.

3. A system according to claim 2 in which symbols on the labels are in photoluminescent materials, means are provided for illuminating the labels with ultraviolet light, and the filters before the matrices selectively transmit the light wavelength range of photoluminescence from the symbols, said filters being substantially opaque to reflected ultraviolet light.

4. A system according to claim 1 in which means are provided for moving labeled containers and the means include a switching means coming into play for a short period of time when a label is in a position to be imaged on the matrix, said switching means actuating electronic gating means for permitting pulses from the limiting and threshold circuits to pass to the digital comparator, the short period of time during which the gates are opened being sufficient to transmit digital pulses from all of the photocells of a matrix.

5. A system according to claim 2 in which means are provided for moving labeled containers 'and the means include a switching means coming into play for a short period of time when a label is in a position to be imaged on the matrix, said switching means actuating electronic gating means for permitting pulses from the limiting and threshold circuits to pass to the digital comparator, the short period of time during which the gates are opened being sufficient to transmit digital pulses from all of the photocells of a matrix.

6. A system according to claim 2 in which a portion of the area of symbols on the label carries symbols in one luminescent material and a portion in another, the luminescence from the two portions being different and the filter before the photocell matrix being in the form of a multizonal filter, the zones corresponding to the image area on the photocell matrix from each of the zones on the label in which the symbols of materials producing an image in electromagnetic radiation correspond to the transmission of the filter. 

1. A system for verifying labels comprising in combination; a. a first photocell matrix; b. means for orienting a label and for imaging it onto the plane of the photocell matrix; c. means for amplifying the output of each individual photocell, d. means for limiting said amplified output to produce voltage pulses having a predetermined voltage with respect to a predetermined threshold voltage, whereby signal outputs in each photocell form a series of digital voltages. e. a digital comparator and means for connecting the digital voltage pulses thereto; f. a second photocell matrix and a second means for orienting a label and imaging it onto a plane of a second photocell matrix; g. Means for amplifying the individual photocell outputs of said matrix; h. means for limiting said amplified outputs to produce voltage pulses with respect to predetermined threshold voltage; i. means for connecting said pulses into the digital comparator and an output from the comparator which depends on the comparison of the digital voltage pulses from the two photocell matrices.
 2. A system according to claim 1 in which each photocell matrix is provided with an optical filter increasing the contrast between radiation from symbols on the label and from the label substrate.
 3. A system according to claim 2 in which symbols on the labels are in photoluminescent materials, means are provided for illuminating the labels with ultraviolet light, and the filters before the matrices selectively transmit the light wavelength range of photoluminescence from the symbols, said filters being substantially opaque to reflected ultraviolet light.
 4. A system according to claim 1 in which means are provided for moving labeled containers and the means include a switching means coming into play for a short period of time when a label is in a position to be imaged on the matrix, said switching means actuating electronic gating means for permitting pulses from the limiting and threshold circuits to pass to the digital comparator, the short period of time during which the gates are opened being sufficient to transmit digital pulses from all of the photocells of a matrix.
 5. A system according to claim 2 in which means are provided for moving labeled containers and the means include a switching means coming into play for a short period of time when a label is in a position to be imaged on the matrix, said switching means actuating electronic gating means for permitting pulses from the limiting and threshold circuits to pass to the digital comparator, the short period of time during which the gates are opened being sufficient to transmit digital pulses from all of the photocells of a matrix.
 6. A system according to claim 2 in which a portion of the area of symbols on the label carries symbols in one luminescent material and a portion in another, the luminescence from the two portions being different and the filter before the photocell matrix being in the form of a multizonal filter, the zones corresponding to the image area on the photocell matrix from each of the zones on the label in which the symbols of materials producing an image in electromagnetic radiation correspond to the transmission of the filter. 